Influence of gear surface roughness on the pitting and micropitting life

Abstract

Pitting and micropitting are the two main gear rolling contact fatigue modes. It is widely accepted that micropitting will lead to pitting; however, the relationship between pitting and micropitting life needs further investigation. In this work, micropitting and pitting tests were performed on an FZG back-to-back test rig using standard FZG PT-C and GF-C gears. The gear tooth profile change due to micropitting and pitting damage was measured in situ in the gearbox using a profilometer after each test. The gear surface roughness parameters were calculated from the measured tooth profile. A Gaussian low pass filter with cut off length [Formula: see text] mm was applied to the measured tooth profile to obtain the waviness. The calculated roughness parameters and the obtained tooth profile with waviness for each test were imported into the KISSsoft software to calculate the contact stress and specific film thickness at the corresponding load stage. Experimental results show that smooth gear surface can reduce or even avoid micropitting damage, but could lead to a reduction in pitting life.

A modified model of Lundberg-Palmgren rolling contact fatigue formula considering the effects of surface treatments

“…In addition, surface roughness also affects fatigue failure modes. Subsurface-initiated contact fatigue failure occurs when the surface roughness is small, while surface-initiated failure appears as the stress concentration near the surface caused by roughness is more prominent [46][47][48]. By introducing a function to describe near-surface failure caused by roughness, Morales-Espejel et al [49] successfully modified the L-P fatigue life model to consider the competitive failure mechanism between surface and sub-surface of bearings.…”

A rolling contact fatigue health prediction model based on load interaction and damage energy accumulation

“…This will increase the shear stress below the surface and reduce the contact life of the parts. 45 y: Hertz contact half-width; z: distance depth from the contact surface; t yz : shear stress on a section of cylindrical roller; r 1 , r 2 : Radius of curvature of part; L: Axial length of part.…”

Operating Performance of External Non-Involute Spur˝and Helical Gears: A Review

“…where h y is the local film thickness on the assumption of smooth surfaces, while R a1 and R a2 are the arithmetic mean roughness values. Bergstedt et al [32] have demonstrated experimentally that the probability of micropitting is lower on a smoother surface. Clarke et al [33] and Liu et al [34] provided an overview of the results of the latest micropitting research.…”